Effect of Acid Slag Treatment on the Inclusions in GCr15 Bearing Steel

By laboratory slag/steel reaction equilibrim experiments, the viriation of oxygen content, inclusion compositions and inclusion sizes were studied. The effect of acid slag treatment on the transition mechanisms of D-type inclusions and the precipitation of TiN inclusions in GCr15 bearing steel were explored. The obtained results showed that the dominant inclusions in steel were plastic and smaller Al 2 O 3 -SiO 2 -MnO. The melting point were lower than 1400°C treated by the acid refining slag of 35.1%CaO-15%Al 2 O 3 -43.9%SiO 2 -6%MgO and there was no TiN found. The evolution of MgO·Al 2 O 3 inclusions is: MgO·Al 2 O 3 → MgO·Al 2 O 3 ·SiO 2 ·MnO → Al 2 O 3 ·SiO 2 ·MnO. Mg and Al from MgO·Al 2 O 3 inclusions were displaced by [Si] and [Mn] in steel liquid , and formation of plastic Al 2 O 3 -SiO 2 -MnO inclusions finally, whose compositions distribution were uniform. Mg and Si, Mn were complementary in inclusions as to the spatial distribution.